Inhibitory effect of a lipopeptide biosurfactant produced by Bacillus subtilis on planktonic and sessile cells of Trichosporon spp.

The present study aimed to investigate the inhibitory effect of a bacterial biosurfactant (TIM96) on clinical strains of Trichosporon. Additionally, the effect of TIM96 on the ergosterol content, cell membrane integrity, and the hydrophobicity of planktonic cells was assessed. The inhibitory activity of TIM96 against Trichosporon biofilms was evaluated by analyzing metabolic activity, biomass and morphology. MIC values ranged from 78.125 to 312.5 μg ml^?1 for TIM96; time-kill curves revealed that the decline in the number of fungal cells started after incubation for 6 h with TIM96 at both MIC and 2×MIC. The biosurfactant reduced the cellular ergosterol content and altered the membrane permeability and the surface hydrophobicity of planktonic cells. Incubation at 10×MIC TIM96 reduced cell adhesion by up to 96.89%, thus interfering with biofilm formation. This concentration also caused up to a 99.2% reduction in the metabolic activity of mature biofilms. The results indicate potential perspectives for the development of new antifungal strategies.     

Comparison of disc diffusion, Etest and broth microdilution for testing susceptibility of carbapenem-resistant P. aeruginosa to polymyxins

Background

New prophylactic and therapeutic tools are needed for the treatment of herpes simplex virus infections. Several essential oils have shown to possess antiviral activity in vitro against a wide spectrum of viruses.

Aim

The present study was assess to investigate the activities of the essential oil obtained from leaves of Artemisia arborescens against HSV-1 and HSV-2

Methods

The cytotoxicity in Vero cells was evaluated by the MTT reduction method. The IC₅₀ values were determined by plaque reduction assay. In order to characterize the mechanism of action, yield reduction assay, inhibition of plaque development assay, attachment assay, penetration assay and post-attachment virus neutralization assay were also performed.

Results

The IC₅₀ values, determined by plaque reduction assay, were 2.4 and 4.1 μg/ml for HSV-1 and HSV-2, respectively, while the cytotoxicity assay against Vero cells, as determined by the MTT reduction method, showed a CC₅₀ value of 132 μg/ml, indicating a CC₅₀/IC₅₀ ratio of 55 for HSV-1 and 32.2 for HSV-2. The antiviral activity of A. arborescens essential oil is principally due to direct virucidal effects. A poor activity determined by yield reduction assay was observed against HSV-1 at higher concentrations when added to cultures of infected cells. No inhibition was observed by attachment assay, penetration assay and post-attachment virus neutralization assay. Furthermore, inhibition of plaque development assay showed that A. arborescens essential oil inhibits the lateral diffusion of both HSV-1 and HSV-2.

Conclusion

This study demonstrates the antiviral activity of the essential oil in toto obtained from A. arborescens against HSV-1 and HSV-2. The mode of action of the essential oil as antiherpesvirus agent seems to be particularly interesting in consideration of its ability to inactivate the virus and to inhibit the cell-to-cell virus diffusion.     

Diatoms as a proxy in reconstructing the Holocene environmental changes in the south-western Baltic Sea: the lower Rega River Valley sedimentary record

This study focuses on diatom assemblages occurring in cores of Late-glacial and Holocene deposits retrieved from the mouth of the lower Rega River valley, of the southern coast of the Baltic Sea. Sediment samples from four cores were the subject of the present study. Diatom-inferred environmental characteristics, e.g., water level; water salinity (conductivity), trophic status and pH, within each core are presented. Diatom assemblage zones (DAZ) were distinguished, based on differences in the distribution of particular ecological groups. Each DAZ appears to be related to environmental changes during the deposition of a given sediment interval. The Late-glacial (Allerød) sediments originated in a shallow lake with increasing concentrations of solutes and nutrients. The Holocene record begins in the early Atlantic Chronozone and the diatoms point to weakly brackish-water sediments deposited in a shallow water environment. During the period of 8,500–5,800 cal year BP sedimentation took place in a shallow embayment and/or lagoon. From ca. 5,800 cal year BP onwards sedimentation took place in a peat bog environment alternating with Aeolian deposition. Changes in diatom community structure imply a close relationship with the climate-controlled eustatic rise of the ocean level and its consequence Littorina transgression. As with other southern Baltic Sea localities, brackish-water diatoms appear in the sediments, signaling the onset of marine transgression somewhat earlier than previously accepted. Differences and similarities in diatom assemblages and the palaeogeographic development of nearby regions within the Baltic Sea basin and lagoons (coastal areas) from different geographic regions, are also discussed.     

Amazonian Amerindians exhibit high variability of KIR profiles

Natural killer cell immunoglobulin-like receptors (KIRs) mediate cell lysis through the recognition of human leukocyte antigen class I complexes in target cells, playing an important role in innate immune response. In this context, disease-based selective pressures could be relevant, leaving signatures detected by population studies. However, most population studies on KIR variability have focused on Europe and Asia, while Americas, Oceania, and Africa remain poorly studied. The aim of this study was to analyze the variability of KIR genes in Amerindian tribes from the Amazon region to infer about their evolutionary history. KIR profiles were estimated in 40 individuals from six Amazonian Amerindian tribes using single specific primer polymerase chain reaction. Twenty-five different profiles were identified, and surprisingly, the haplogroup A frequency was the lowest observed in human populations (16%). Results showed also that KIR variability was higher in this group in contrast to Venezuelan Amerindians. Principal components analysis evidenced that Amerindians formed a separated group from other worldwide populations and showed a higher intraethnic differentiation in comparison to other ethnic groups. Such pattern may reflect small effective size and intense genetic drift. However, because of the role of KIR in immune response, selective pressures cannot be entirely ruled out.     

Apoptosis in HEp-2 cells infected with Ureaplasma diversum

Background

Bacterial pathogens have many strategies for infecting and persisting in host cells. Adhesion, invasion and intracellular life are important features in the biology of mollicutes. The intracellular location of Ureaplasma diversum may trigger disturbances in the host cell. This includes activation or inhibition of pro and anti-apoptotic factors, which facilitate the development of host damage. The aim of the present study was to associate U. diversum infection in HEp-2 cells and apoptosis induction. Cells were infected for 72hs with four U. diversum clinical isolates and an ATCC strain. The U. diversum invasion was analyzed by Confocal Laser Scanning Microscopy and gentamicin invasion assay. The apoptosis was evaluated using pro-apoptotic and anti-apoptotic gene expression, and FITC Annexin V/Dead Cell Apoptosis Kit.

Results

The number of internalized ureaplasma in HEp-2 cells increased significantly throughout the infection. The flow cytometry analysis with fluorochromes to detect membrane depolarization and gene expression for caspase 2, 3 and 9 increased in infected cells after 24 hours. However, after 72 hours a considerable decrease of apoptotic cells was observed.

Conclusions

The data suggests that apoptosis may be initially induced by some isolates in association with HEp-2 cells, but over time, there was no evidence of apoptosis in the presence of ureaplasma and HEp-2 cells. The initial increase and then decrease in apoptosis could be related to bacterial pathogen-associated molecular pattern (PAMPS). Moreover, the isolates of U. diversum presented differences in the studied parameters for apoptosis. It was also observed that the amount of microorganisms was not proportional to the induction of apoptosis in HEp-2 cells.     

Contrasting responses to environmental changes by pine (Pinus sylvestris L.) growing on peat and mineral soil: An example from a Polish Baltic bog

A comparison of the tree-ring width of pines growing in areas adjacent to a peat bog and on a Baltic raised bog dome suggests that cambium activity in each tree group is affected by different factors. The study was aimed at pinpointing effects of meteorological factors on two pine populations growing under different hydrological conditions. The study further sought to identify periods during which anthropogenic pressure affected the two populations. The pines growing on mineral soil were characterised by ring-width growth–climate responses typical of this part of Europe, whereas the tree-ring growth of the pines growing on the peat bog showed no unequivocal relationship with meteorological conditions. The tree-ring width growth dynamics of that population responded primarily to changes in the level of the groundwater table. These changes were associated with human activities over the last two centuries. The development of the tree stands on the peat bog and in its immediate vicinity was reconstructed using this assumption and available historical evidence. A banding drainage ditch dug around 1880 resulted in the drying of the peat bog, the introduction of pines, and the forestation of the bog. Digging of central ditches (in the 1960s) resulted in periodic desiccation of the bog surface and reduction of the tree-ring widths; similar responses were observed in the 1980s as a consequence of the deepening and opening of the drainage ditches. The recent years are characterised by decreasing ring-width growth as a result of the damming of drainage ditches. Damming resulted in an increase of the groundwater table level in the bog and in a partial inundation of tree roots. This partial inundation interfered with gas exchange and adversely affected the health status of the pines studied. Our results allow conclusions to be drawn regarding peat bog palaeohydrology and facilitate absolute dating of changes associated with anthropogenic transformations. In active nature protection, such data are of key importance for understanding the functioning of a peatland and for planning active conservation measures.     

Last millennium palaeoenvironmental changes from a Baltic bog (Poland) inferred from stable isotopes, pollen, plant macrofossils and testate amoebae

The Baltic coast of Northern Poland is an interesting region for palaeoclimatic studies because of the mixed oceanic and continental climatic influences and the fact that the dominance of one or the other of these two influences might have changed over time. Also, unlike many more intensively studied regions of Europe, human impact in the region was rather limited until the 19th century. We present a 1200-year high-resolution record from Stążki mire, an ombrotrophic bog located 35 km from the Baltic Sea coast. Using testate amoebae, stable isotopes (δ¹³C) of Sphagnum stems, pollen, plant macrofossils and dendroecological analyses, our aims were to: 1) reconstruct the last millennium palaeoenvironment in the study site and its surroundings, 2) identify the major wet–dry shifts, 3) determine if those events correlate with climate change and human impact, 4) assess the resilience of the Baltic bog ecosystem following human impact, and 5) compare the palaeo-moisture signal from the Baltic coast with records from more oceanic regions. Two dry periods are inferred at AD 1100–1500 and 1650–1900 (–2005). The first dry shift is probably climate-driven as pollen record shows little evidence of human indicators. The second dry shift can be related to local peat exploitation of the mire. In the 20th century additional limited drainage took place and since ca. AD 1950 the mire has been recovering. From 1500 AD onwards all proxies indicate wetter condition. The beginning of this wet shift occurred during the Little Ice Age and may therefore be a climatic signal. The macrofossil data show that Sphagnum fuscum dominated the pristine mire vegetation but then declined and finally disappeared at ca. AD 1900. This pattern is comparable with the timing of extinction of Sphagnum austinii (= Sphagnum imbricatum) in the UK. This study illustrates the value of high-resolution multi-proxy studies of peat archives to assess the magnitude of anthropogenic land-use changes. This study presents the first direct comparison of testate amoebae and stable isotope data from the same core. The two proxies correlate significantly throughout the record and most strongly for the latter part of the record when most of the variability was recorded.